Bayard (The Black Tower) shifts smoothly between present-day America and Elizabethan England in this superb intellectual thriller. At the Washington, D.C., funeral of document collector Alonzo Wax, who committed suicide, Bernard Styles, an elderly Englishman and rival collector, approaches Henry Cavendish, an Elizabethan scholar and the executor of Wax's estate, whose academic reputation suffered grievous harm after he authenticated a new Walter Ralegh poem that was later exposed as a hoax. Styles offers Cavendish $100,000 to locate a prize Wax had borrowed, a recently discovered Ralegh letter that may prove the existence of the School of Night, a secret debating club whose members included playwright Christopher Marlowe. Murder complicates the search for the letter. The author's persuasive portrayal of undeservedly obscure real-life scientist Thomas Harriot, a member of the school, enhances a plot with intelligence and depth. (Apr.)